Abstract To better support the needs of our aging vivarium, the Mutant Mouse Resource and Research Center at the University of California, Davis (MMRRC-UCD) is driven to improve the infrastructure and equipment within our M3 high-level rodent barrier facility. As a premier distributor of mutant mouse models, the infrastructure of our barrier is a critical factor influencing the health and well-being of the animals we produce and distribute worldwide, currently serving 41 countries. The MMRRC-UCD is the largest center of the four NIH-funded consortiums, and specializes in the cryopreservation and distribution of valuable mutant mouse models. In continued efforts to improve the efficiencies of our operations we have analyzed the deficiencies hindering our optimal production and identified a key factor being aged and outdated equipment. Older animal housing and procedure equipment can lead to increased energy and water use, in addition to excessive noise and vibrations compared to more advanced modernized technologies, all leading to increase stress to the animal. As a result, animal production may be compromised and the costs of operations increased. The laboratory animal community has been strong advocates to promote the ?3R?s? being Replacement, Reduction and Refinement. However, we are now in an era when we must also advocate for what we envision as the ?5E?s?: Efficiencies, Exclusion, Ergonomics, Enrichment, and Education. Our goal is to improve the infrastructure at our barrier facility by implementing lean management principles with an environmentally resourceful emphasis using our innovative 5E?s approach. The current proposal requests funds to upgrade outdated animal transfer stations and biosafety cabinet in the M3 Barrier Facility. Additionally, we will discontinue the use of water bottles as a water source for the animals and convert to using HydropacTM pouches to provide a sterile water source, thus reducing the risk of pathogens and decreasing the environmental resources used. The MMRRC- UCD strives to advantageously integrate innovative concepts for higher efficient, exclusive and ergonomic vivarium designs to transform our standard rodent barrier facility into a state of the art prototype of a Lean- Green animal research facility, to guild other institutions to enable our principles to be applied globally.